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Full-Text Articles in Life Sciences

Using Plot Photographs To Estimate Tundra Vegetation Cover In Northern Alaska, Hana Christoffersen Aug 2022

Using Plot Photographs To Estimate Tundra Vegetation Cover In Northern Alaska, Hana Christoffersen

Masters Theses

Plot photography can provide a quick, robust method to measure vegetation, especially in polar environments where logistics can be expensive and challenging. The success and widespread adoption of plot photography in the Arctic hinges on the accuracy of image analysis and data product interpretation. The relative cover of eight vegetation classes was estimated using a point frame and digital camera across thirty, 1-m2 plots at Utqiaġvik, Alaska from 2012 to 2021. Geographic object-based image analysis (GEOBIA) was applied to generate objects and classify the three band (red, green, blue) images. Machine learning classifiers (random forest, gradient boosted model, classification …


Evaluating Current And Future Potential Distribution Of Epiphytic Orchids In The Congo Basin With Ecological Niche Models, Michael L. Ngoh Aug 2022

Evaluating Current And Future Potential Distribution Of Epiphytic Orchids In The Congo Basin With Ecological Niche Models, Michael L. Ngoh

Masters Theses

The Congo Basin Forest harbors a rich diversity of epiphytic communities, with the Orchidaceae alone making up more than 50% of all epiphytes in the region. Despite the huge diversity of epiphytes, many species, including epiphytic orchids, are at risk to a diverse array of threats. Climate change for instance poses severe threats to epiphytic orchids due to elevated temperatures, prolonged periods of droughts, as well as reduced rainfall across the Congo Basin Forest. In this study, we used ecological niche modeling and GIS techniques to identify spatial patterns of species richness, potential future climate refugia, and novel climatic suitability …


The Spatial Ecology And Habitat Selection Of A Spotted Turtle (Clemmys Guttata) Population In Southwest Michigan, Michela Coury May 2022

The Spatial Ecology And Habitat Selection Of A Spotted Turtle (Clemmys Guttata) Population In Southwest Michigan, Michela Coury

Masters Theses

Turtles are arguably the most threatened group of vertebrates on the planet. Anthropogenic influences such as habitat loss and fragmentation, road mortality, subsidized predators, climate change, and illegal collection have contributed to their global decline. Understanding which isolated populations of turtles are viable despite these synergistic threats is crucial for making conservation and management decisions. In Michigan, the spotted turtle (Clemmys guttata) is a threatened species subjected to many negative anthropogenic influences that accelerate its rapid population decline. In order to properly sustain their populations, the goal of my research was to investigate relevant factors that help us …


Climate-Driven Selection Results In Powerful Geographic Framework For Predicting Phenotype, Alexandra Neild May 2022

Climate-Driven Selection Results In Powerful Geographic Framework For Predicting Phenotype, Alexandra Neild

Masters Theses

Our ability to prepare for and mitigate the likely ecological and evolutionary impacts of climate change largely depends upon our ability to predict the phenotypic responses of organisms that allow them to persist, adapt, and migrate along environmental stress gradients. Using fifteen populations of cottonwoods, a dominant riparian forest tree, that are distributed along elevation gradients and represent three genetic provenances, we hypothesized and show that: 1) populations within a provenance demonstrate parallel evolutionary responses to climatic gradients associated with elevation; and 2) the evolutionary effects of elevation on bud-break phenology varied by provenance. Across all populations, we find strong …


Songbird-Mediated Insect Pest Control In Low Intensity New England Agriculture, Samuel J. Mayne Mar 2022

Songbird-Mediated Insect Pest Control In Low Intensity New England Agriculture, Samuel J. Mayne

Masters Theses

Global agricultural intensification has caused large-scale wildlife declines, but agricultural lands that maintain natural habitats can support healthy wildlife populations and receive significant ecosystem services from these natural communities. However, how on-farm biodiversity results in beneficial ecosystem services is highly variable and is reported to differ among taxa and guilds. One group that has attracted attention for their potential beneficial role in reducing pest abundance are birds. Understanding the role of bird communities and individual species in pest control could be important for managing farms under a low intensity agroecological framework. In New England, farmers are increasingly applying low intensity …


Low-Head Dam Removal Increases Functional Diversity Of Stream Fish Assemblages, Adam Christopher Jones Jan 2022

Low-Head Dam Removal Increases Functional Diversity Of Stream Fish Assemblages, Adam Christopher Jones

Masters Theses

Despite the growing number of dam removals to date, very few have been studied to understand their impacts on stream fish communities. Despite being the most common type of dam in the U.S., an even smaller proportion of studies focus on the impacts of low-head dam removals, instead, focusing on the impacts of removal of larger dams. In this study, two previously impounded Illinois rivers were monitored to assess the impacts of low-head dam removal on the functional assemblage of stream fishes. This was accomplished by aggregating fishes into habitat and reproductive guilds, relating community changes to habitat, environmental metrics, …